1. Field of the Invention
The present invention relates to a three-dimensional photonic crystal and a process for the production thereof as well as a probe used therefor, and more particularly to a three-dimensional photonic crystal into which an optical phase shift region (defect region) can be inserted arbitrarily, so that which is used suitably in case of constituting semiconductor lasers, optical waveguides and the like, and a process for the production thereof as well as a probe used therefor.
2. Description of the Related Art
Heretofore, a photonic crystal having a similarity as that of solid crystal and involving an artificial periodic structure has been known. More specifically, photonic crystal is the one having a two- or a three-dimensionally periodic structure wherein two or more types of dielectrics, semiconductors, metals and air are alternately disposed in a repeated manner with a period corresponding to around optical wavelengths.
In the present specification, it is to be noted that photonic crystal having a two-dimensionally periodic structure is referred to as “two-dimensional photonic crystal”, while photonic crystal having a three-dimensionally periodic structure is referred to as “three-dimensional photonic crystal”.
In solid crystal, atoms are disposed periodically wherein a wave of electron exhibits a certain particular behavior while capturing a periodicity of the crystal. Likewise, in a periodic structure of photonic crystal, not a wave of electrons, but a wave of light exhibits a certain particular behavior, which is determined by energy dispersion characteristics and referred to as photonic band. Furthermore, in photonic crystal, it is possible to produce a forbidden gap wherein existence of light can be forbidden, which is referred to as “photonic bandgap”.
From the facts as described above, it is assumed that there is a high possibility being capable of freely controlling light by an optical device constituted from three-dimensional photonic crystals, as in the case where a semiconductor device can control freely electrons.
For this reason, a manner for producing three-dimensional photonic crystals has been proposed heretofore as a prerequisite for fabricating an optical device constituted by three-dimensional photonic crystals, for example, three-dimensional etching method, wafer fusion laminating method, automatic cloning method or the like method is known in this respect.
Three-dimensional etching method means a method wherein a substrate is etched at various angles to produce three-dimensional photonic crystals involving three-dimensional structures. Furthermore, wafer fusion laminating method is the one wherein a plurality of semiconductors formed into striped shapes are accurately positioned to laminate with each other by the use of a laser beam diffraction pattern, whereby three-dimensional photonic crystals involving three-dimensional structures are produced. Moreover, automatic cloning method is the one wherein an irregular surface has been previously formed on a substrate, and crystals are grown on the irregular surface retaining the surface morphology, whereby three-dimensional photonic crystals having three-dimensional structures are prepared.
However, any of the above-described conventional methods is not sufficient for producing three-dimensional photonic crystals applicable to optical devices, so that a proposition for a practically effective and novel method has been strongly demanded.